A closer look at microplastics, our daily cup of tea, and what the science really tells us.
There are few things more familiar than putting the kettle on.
Tea is part of the rhythm of everyday life. Morning tea, afternoon tea, one before bed — for many of us, it's something we barely think about.
But there is a small detail worth thinking about.
What is your teabag actually made from?
Some teabags contain plastic, either within the bag itself or as part of the material used to seal it. When that bag is placed into hot water, microscopic particles can potentially migrate into the drink.
You may have seen some rather alarming numbers online.
One cup of tea.
Billions of plastic particles.
It is a remarkable claim.
But as scientists, we think the story is much more interesting when you look beyond the headline.
The 11.6 billion particle question
In 2019, researchers at McGill University published a study investigating plastic teabags.
They found that steeping a single plastic teabag at approximately 95°C released an estimated:
11.6 billion microplastic particles
and
3.1 billion nanoplastic particles
into the tea.
The study examined teabags made from materials including nylon and polyethylene terephthalate (PET), and the results were published in the peer-reviewed journal Environmental Science & Technology. (ACS Publications)
It was an extraordinary result, and understandably it received worldwide attention.
But there is an important part of the story that is often missing from the headlines.
The number has since been challenged.
The German Federal Institute for Risk Assessment (BfR) reviewed the research and carried out its own experiments.
Rather than simply counting everything visible under a microscope, the researchers used micro-Raman spectroscopy, which can help identify the chemical composition of individual particles.
They found approximately 5,800 to 20,400 microplastic particles larger than 1 micrometre per teabag.
That is two to three orders of magnitude lower than the 2.3 million particles larger than 1 micrometre reported in the original study. The BfR also concluded that many of the particles counted in the original experiment were likely not microplastics at all, but oligomers associated with the plastic material. (Bundesinstitut für Risikobewertung)
So, should we tell you that your cup of tea contains 11.6 billion microplastics?
No.
That would be presenting a disputed figure as established fact.
What we can say with considerably more confidence is that plastic-containing teabags can contribute measurable microscopic particles to hot water, and research into exactly how much is released is still developing. A recent systematic review also highlights considerable variation between studies depending on the teabag material and the analytical method used. (PubMed Central (PMC))
And that distinction matters.
Good science isn't about finding the scariest number.
It's about understanding how that number was obtained.
What exactly is a microplastic?
Microplastics are extremely small pieces of plastic.
They can be produced deliberately at microscopic sizes, or created when larger plastic products gradually break down.
Even smaller particles are referred to as nanoplastics.
At these scales, we cannot see them floating around in our cup of tea. They are simply too small.
And this is not an issue unique to tea.
Microplastics are now being investigated across our food, water, air and household environments. They can come from packaging, textiles, household dust, food preparation and many other everyday sources.
The important point is that exposure is widespread.
What scientists are still working to understand is what different levels and types of exposure mean for us over a lifetime.
Where have microplastics been found in humans?
This is perhaps the most interesting part of the story.
Researchers have now reported microplastics in a number of human biological samples and tissues, including blood, lungs, placenta, breast milk and reproductive tissues.
Finding a particle in a human tissue does not automatically mean that it has caused harm.
That is a distinction we think is extremely important.
But it does tell us something significant:
At least some plastic particles can get beyond the digestive system and enter parts of the human body.
Researchers have even detected microplastics in human reproductive tissues.
A study examining human testicular tissue and semen reported the presence of several types of plastic, including polyethylene, polystyrene and PVC.
Again, this does not prove that microplastics cause infertility.
It does, however, give researchers another important question to investigate:
What does long-term exposure mean for reproductive health?
That question is still open.
And then there is the chemical side of plastics
There is another part of this conversation that is sometimes overlooked.
When we talk about plastic exposure, we are not necessarily talking only about the physical particles themselves.
Plastics can contain a wide variety of chemical additives.
Two of the most widely discussed groups are phthalates and bisphenols, including BPA.
These chemicals are of particular interest because some can interfere with the body's hormonal signalling system. They are therefore classified as endocrine-disrupting chemicals, or EDCs.
And this is where the conversation around plastic becomes considerably bigger than a teabag.
We encounter plastic and plastic-associated chemicals through packaging, food storage, cosmetics, household products, clothing and countless other everyday objects.
Which brings us to a recent documentary that has been generating quite a lot of conversation.
What can we learn from The Plastic Detox?
Netflix's The Plastic Detox follows six couples experiencing unexplained infertility as they attempt to significantly reduce their exposure to plastics and plastic-associated chemicals over approximately three months.
Working with environmental and reproductive epidemiologist Dr Shanna Swan, the couples changed a surprisingly large number of everyday habits.
They altered the products they used, how they stored food, what materials they wore and how they interacted with everyday plastics.
The aim was simple:
Could reducing everyday exposure to plastic-associated chemicals change what was measurable inside the body?
The results were certainly interesting.
Netflix reports that several participants experienced substantial reductions in their exposure to chemicals including BPA, with BPA becoming undetectable in many participants. During the period covered by the documentary, three of the six couples became pregnant. (Netflix)
It is an intriguing result.
But perhaps the most useful message isn't that plastic has been proven to cause infertility.
It hasn't.
The documentary was not a large, randomised clinical trial, and there are many factors involved in fertility.
What it does demonstrate is something much simpler:
Our exposure to some plastic-associated chemicals can change when our everyday habits change.
That is an important finding in itself.
And it gives scientists a useful starting point for larger, more controlled research. Dr Swan and her team are now working towards a substantially larger study. (Netflix)
So, should we be worried about our tea?
This is where we think a little perspective is helpful.
The current evidence does not justify telling people that drinking tea from a plastic-containing teabag is going to make them ill.
The BfR's current assessment states that, based on the evidence available, health impairments from the microplastic exposure associated with teabags are not expected. (Bundesinstitut für Risikobewertung)
At the same time, researchers continue to investigate the potential biological effects of micro- and nanoplastics, particularly because our exposure is so widespread and occurs over many years.
So perhaps the sensible response isn't fear.
It's simply awareness.
How can you reduce your exposure?
Fortunately, this is one of those changes that doesn't need to be complicated.
If you drink tea every day, you can:
Choose genuinely plastic-free teabags
Look for manufacturers that clearly state that their teabags contain no plastic, rather than relying solely on terms such as plant-based, biodegradable or compostable.
Those terms can mean different things, and a plant-derived polymer is still a polymer.
Look at the material
If a manufacturer clearly identifies the bag as being made from paper, cellulose or another plastic-free material, that's much more useful than simply seeing a green leaf on the packaging.
Consider loose-leaf tea
A reusable stainless-steel infuser removes the teabag itself from the equation altogether.
It doesn't mean your tea is magically free from every possible source of microplastics — exposure is much more complicated than that — but it does remove one unnecessary source.
And perhaps most importantly:
Don't panic.
You don't need to throw away every teabag in your kitchen tonight.
At Reef & Stone, we believe in better questions
There is an enormous amount of information online about microplastics.
Some of it is genuinely fascinating.
Some of it is exaggerated.
And some of it takes a single scientific finding and turns it into a frightening conclusion that the research simply doesn't support.
We'd rather do things differently.
We believe in looking at the evidence, understanding its limitations and then making sensible choices from there.
The research around microplastics is evolving quickly. We don't yet have every answer.
But we do know that our exposure is widespread.
We do know that plastic particles have been detected in human biological samples.
And we do know that reducing exposure to some plastic-associated chemicals is possible through relatively simple changes in everyday life.
So next time you make a cup of tea, take a look at the little bag sitting in your mug.
It might just make you ask a slightly better question.
And we think that's a good place to start.
The science behind this article
We believe that if we're going to talk about science, you should be able to see where it comes from.
Hernandez et al. (2019), Environmental Science & Technology
Plastic Teabags Release Billions of Microparticles and Nanoparticles into Tea. The original study reporting 11.6 billion microplastic and 3.1 billion nanoplastic particles from a plastic teabag under its experimental conditions. (ACS Publications)
German Federal Institute for Risk Assessment (BfR), 2025
Independent assessment of the teabag research, including the methodological concerns surrounding the original particle counts and its own measurements of approximately 5,800–20,400 particles larger than 1 µm per teabag. (Bundesinstitut für Risikobewertung)
Systematic review of micro- and nanoplastics in teabags, 2026
A review of the available evidence examining teabag materials, brewing conditions and differences between analytical methods. (PubMed Central (PMC))
The Plastic Detox, Netflix, 2026
Six couples reducing their exposure to plastic-associated chemicals over three months, with changes in exposure and fertility-related measurements documented during the project. (Netflix)
The science surrounding microplastics is developing rapidly. Where evidence is uncertain or contested, we believe it's important to say so.